Evolution of human intelligence

Hello livinus

We do know why the brain increased in size as a result of the adoption of bipedalism, niche changes and overall increased activities related to both hands and legs. However, the shrinking of the brain size with intelligence seems unlikely. Perhaps your friend meant the shrinking of direct function-area relations in the brain over time (phrenology). If you compare the brains of fish, monkeys, rodents and the human, we tend to have a "smaller" % of the brain directly related to a specific function. In other words, we have far less "instinctual' behavior by comparison, and much more "association" areas. The brain area is almost distributed into a 50% direct function :50% association. So with the evolution from a primate-like brain over time, there was a loss of instinct behavior areas. By comparison to those organisms and humans one more time, we are the only beings that can further process our needs through social moral and ethical/responsible attributes. This is by virtue of our brain's frontalization. Therefore, I do not think our intellectual capacities have gone down. If anything, I think we are becoming even more intelligent with enhanced capacities.

I hope this helps

Could you or anyone provide a valid source to back this claim? I want to read the research behind it before I can argue against or for this notion.

Brain size doesn't always correlate with intelligence.

Hello bioman

I did a quick search about this. I didn't look up any articles yet - don't really have enough time on my hands right now. But, the more I read, the more the issue got complicated. What I understood was that there still is no clear link explaining the decrease in size and why. The topic is gaining the attention slowly. Although, when reading you start to get ideas and think about all sorts of factors that could have a say in this issue. Try these links.

http://discovermagazine.com/2010/sep/25-modern-humans-smart-why-brain-shrinking

http://humanorigins.si.edu/human-characteristics/brains

I would start with the second link first. It gives a general overview. The first link goes more into details and honestly, was the link that got me thinking.. And now I have a headache
Such topics are really demanding to sit and go through. You could spend an entire day reading and end up even more confused.

Let me know what you think =)

Benefits and Costs of a Big Brain

Benefits

The modern human brain can:

- store many decades worth of information;

- collect and process information, then deliver output, in split seconds;

- solve problems and create abstract ideas and images.

Costs

- A big brain gobbles up energy. Your brain is 2 percent of your body’s weight but uses 20 percent of your oxygen supply and gets 20 percent of your blood flow.

- Large brains mean large heads, making childbirth more difficult and painful for human mothers than for other primates.